it is easier to have a circuit on the amp, that will flip a circuit break. Nakamichi's can't be used on stage as the have a clip circuit, a heat circuit, and a speaker over amped circuit and they cut off alot unless you are using 10 gauge wire to start. Great amps though.
On Fri, 10 Apr 2009, Scott Howell wrote: > Wow, we had a few parties at our house growing up that my folks never > knew about, but we sure as hell never let things get out of hand. Well > it was more like my sisters had the party and I either stayed around > to make sure things stayed cool or came back to find they exercised > good sense and only had a few friends. My kid would be paying for a > really long time and I bet that will be the last party that girl ever > has and certainly she'll have a real respect for speakers. > Funny you mention the cut off circuits and such. My bass amp has a > similar circuit mainly for the horn, but of course it is built to > handle the lower frequencies, but I still wonder how it remains cool > in such a box. > > On Apr 10, 2009, at 1:55 AM, Ray Boyce wrote: > >> >> >> Friends recently returned from a couple of weeks away to find one of >> their >> teenagers had hosted a party during their absence. As well as >> discovering >> chipping in the kitchen's marble bench top and a missing iPod, they >> also >> found none of their hi-fi speakers were working. >> >> Speakers have delicate electrical windings behind their cones called >> voice >> coils. These are intricate little things that are surrounded by a >> fixed and >> usually very powerful magnet. >> >> The amplifier feeds electricity into the voice coils in varying >> amounts and >> the resultant electrical field drives the coil, which is connected >> to the >> cone, back and forth along the inside of the magnet. This moves the >> cone in >> and out, generating sound waves. The voice coil is, therefore, the >> very >> heart of the speaker. >> >> The voice coils inside these particular speakers had been reduced to >> gloop. >> They had melted and the bad news for my friends was that replacing >> voice >> coils is so complex and expensive that it's often best to throw away >> the >> speakers and buy new ones. Replacing melted voice coils can get so >> complex >> that lots of repairers don't want the work. >> >> It's often not just a matter of putting in a new voice coil. >> Frequently, the >> heat generated has also damaged components around the coil and, in >> some >> cases, melted the adhesives used in the speaker's construction. >> >> So why do voice coils melt? I wasn't at the party (it sounded like a >> ripper), but I suspect two things happened. First, someone cranked >> up the >> volume and, second, these being young people, someone turned up the >> bass as >> high as it would go. >> >> Most of the energy applied to a voice coil winds up as heat, which >> isn't a >> problem at normal listening levels when it can be dissipated by the >> air >> around it. But at high power levels, heat builds up faster than it >> can be >> dissipated and, if these high power levels are maintained, >> something's got >> to give. Usually, it's the voice coil. It melts, taking the insulation >> separating the windings along with it. >> >> Turning up the bass makes this happen faster. Speakers are placed in >> cabinets because the air inside the cabinet forms a natural suspension >> system for the cone as it punches in and out. This is why the internal >> volume of a cabinet has to be spot on, and varies from cone to cone, >> depending on its size and strength. >> >> But at very low frequencies, the air inside the cabinet provides >> little or >> no buffering, meaning there's nothing to stop the cone moving in and >> out as >> far as it can possibly travel. By turning up the bass all the way, the >> speaker is being directed to favour low frequencies over all others, >> so the >> cone works even harder. And things just keep getting hotter. >> >> Had anyone at the party been paying attention, they would have heard >> the >> danger signals. The speakers would have been distorting horribly, >> producing >> ragged, fuzzy bass that sounded ill-defined. Listening to it would >> have been >> uncomfortable. But maybe no one noticed, or maybe if anyone did and >> turned >> the music down, they were overruled by others. >> >> The teenager involved is working weekends to reimburse her parents >> and has >> discovered that speakers, while not at all cheap, have nothing on >> marble >> bench tops. >> >> Speaker safeguards >> >> When you're buying speakers, whether it be for the first time or to >> replace >> those that have been beaten to death, it's worth having a talk to a >> specialist supplier about how you're going to use them. If you often >> play >> music loud and long, finding speakers with sophisticated heat >> dissipation >> technology or automatic cut-outs is well worth the effort involved. >> >> Some speakers have sophisticated cooling provisions built in, such >> as vented >> pole pieces and heat sinks. Others have circuitry that shuts them >> down when >> they get too hot or energy levels get too high. They simply stop >> working >> until things return to normal. >> >> Some amplifiers and car stereos have a "loud" switch that increases >> bass. >> These are designed to emphasise bass notes at very low listening >> levels when >> they're at their weakest, but activating the switch at high volume >> can lead >> to all the problems we've been talking about here. In many cases >> protective >> circuitry ensures the loud switch has no effect above certain pre-set >> volumes anyway. >> >> [Non-text portions of this message have been removed] >> >> > > > > [Non-text portions of this message have been removed] > >
